Why? Well, for starters, he’s now the man charged with adding an 18th banner to those rafters after being announced as the 17th head coach in franchise history.

President of basketball operations Danny Ainge welcomed Stevens, who at 36 becomes the youngest coach in the NBA, two days after formally announcing that he had hired Stevens away from Butler University.

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Stevens will lead the Celtics into a new era that will likely look much different from the final years of his predecessor, Doc Rivers. The Celtics, having traded icons Paul Pierce and Kevin Garnett, are entering a rebuilding phase that will test Stevens’ ability as a basketball teacher.

Stevens said while he’s aware of the high-profile failures of previous college coaches in the NBA (such as former Celtics coach Rick Pitino and John Calipari), he’s not deterred by their performances.

Instead, Stevens said the Celtics’ approach as they recruited him – which he called professional and process-driven – impressed him and made him confident he can succeed in Boston the same way he did at Butler.

Ainge noted that the history of college coaches flaming out in the NBA seemed to loom over the hiring of Stevens, and made it necessary for the Celtics to prove to their new coach they’re arming him to succeed.

“He had to take a leap of faith in us as an organization,” Ainge said.

One of his first challenges may be developing rapport with Rajon Rondo, the team’s mercurial All-Star point guard. As an established star, Rondo may be skeptical about buying into the vision of a 36-year-old coach of a rebuilding team.

But Stevens said he talked with Rondo on Thursday and the two had a fruitful opening conversation.

“There is no bigger fan of Rajon Rondo than me,” Stevens said. “The way he plays, his instincts, his ability to make other people better.”

Stevens said Rondo gave him “really good” feedback.

“I have so much respect for how he sees the court,” coach said. “I’m looking forward to sitting down and learning from him.”

On Thursday, a source close to Rondo who has talked with the guard since the Stevens hiring told the Globe that Rondo is looking at the move with a “completely open mind.”

Stevens came on Ainge’s radar as an NBA candidate within the past few years – and he even called him the “best coach in college basketball” during Butler’s 2010 championship loss to Mike Krzyzewski’s Duke team. (That was the first of back-to-back appearances in the national championship game that Stevens led Butler to from the small-conference Horizon League.)

“I have watched and admired his poise, his intelligence,” Ainge said.

Another quality stuck out for Ainge.

“The difference is his humility,” the Celtics boss said, in comparing Stevens to past college coaches who have made the jump to the NBA.

An NBA source said Thursday that Stevens’ personality may make him a good candidate to succeed where previous NCAA coaches failed in the pros.

“He’s the anti-[John] Calipari, the anti-[Rick] Pitino. Those guys, they think it’s about them,” the source said. “He’s going to learn that it’s about the players and that’s going to help.

“Everything is a risk, but this is a good risk.”

And the Celtics, since they are entering a rebuilding phase, have the luxury of being able to take a chance on a coach like Stevens if they believe his style will translate to the NBA.

Ainge said he was almost instantly comfortable with Stevens and the decision to hire him. So much so that he wanted to make Stevens’ contract reflect the Celtics’ confidence in him.

“I don’t think there’s any other coach in the NBA with a 6-year commitment,” Ainge said. “We’re investing in him.”

Stevens, while noting that “winning championships” is his goal, also tried to display some of that humility.

“I won’t be right in every decision. I’m going to make a lot of mistakes,” he said.

“But we will bust it to make sure we won’t make that same mistake again.”

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